[CRIU] [PATCH CRIU 08/14] restore/net/ipv6: net device and def/all configuration

[Pavel Tikhomirov]

Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.

----Пользователь Pavel Emelyanov написал ----

> On 04/04/2016 06:38 PM, Pavel Tikhomirov wrote:
> > On 04/04/2016 06:29 PM, Pavel Tikhomirov wrote:
> >>
> >>
> >> On 04/04/2016 06:03 PM, Pavel Emelyanov wrote:
> >>> On 04/04/2016 05:46 PM, Pavel Tikhomirov wrote:
> >>>>
> >>>>
> >>>> On 04/04/2016 05:40 PM, Pavel Emelyanov wrote:
> >>>>> On 04/04/2016 04:58 PM, Pavel Tikhomirov wrote:
> >>>>>>
> >>>>>>
> >>>>>> On 04/04/2016 04:38 PM, Pavel Emelyanov wrote:
> >>>>>>> On 04/04/2016 01:30 PM, Pavel Tikhomirov wrote:
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> On 04/04/2016 01:16 PM, Pavel Emelyanov wrote:
> >>>>>>>>>
> >>>>>>>>>> @@ -163,9 +163,11 @@ static int net_conf_op(char *tgt, int
> >>>>>>>>>> *conf, int n, int op, char *proto,
> >>>>>>>>>>                  continue;
> >>>>>>>>>>              }
> >>>>>>>>>>              /*
> >>>>>>>>>> -         * If dev conf value is the same as default skip
> >>>>>>>>>> restoring it
> >>>>>>>>>> +         * If dev conf value is the same as default skip
> >>>>>>>>>> restoring it,
> >>>>>>>>>> +         * mtu may be changed by disable_ipv6 so we can not skip
> >>>>>>>>>> +         * it's restore
> >>>>>>>>>>               */
> >>>>>>>>>
> >>>>>>>>> No, this means that we should restore mtu after disable_ipv6.
> >>>>>>>>> And we still can check
> >>>>>>>>> for it to match default value.
> >>>>>>>>
> >>>>>>>> Imagine situation:
> >>>>>>>> 1)restore disable_ipv6 for default
> >>>>>>>> 2)restore mtu for default
> >>>>>>>> 3)create eth0
> >>>>>>>> 4)restore disable_ipv6 for eth0
> >>>>>>>> 5)restore mtu for eth0
> >>>>>>>>
> >>>>>>>> After step 3 both default and eth0 mtu are set to default value. But
> >>>>>>>> after step 4 eth0's one can possibly change. So do you mean we
> >>>>>>>> need to
> >>>>>>>> first restore both default/disable_ipv6 and eth0/disable_ipv6 and
> >>>>>>>> only
> >>>>>>>> after that restore default/mtu ?
> >>>>>>>
> >>>>>>> No. By step 5 will eth0's mtu match the default mtu?
> >>>>>>
> >>>>>> By step 5 we will have eth0/mtu(in image) equal to default/mtu(in
> >>>>>> image)
> >>>>>> equal to default/mtu(sysctl) but not equal to eth0/mtu(sysctl).
> >>>>>
> >>>>> How can this happen? Anything in the image should match the same in
> >>>>> sysctl-s
> >>>>> on the dump side, so if eth0.mtu == default.mtu in image, then the
> >>>>> same is
> >>>>> true for sysctls on dump side. Why should it differ on restore?
> >>>>
> >>>>   From comment to 06/14 patch:
> >>>>
> >>>>   >In
> >>>> addrconf_sysctl_disable->addrconf_disable_ipv6->dev_disable_change:
> >>>>   >On addrconf_notify + NETDEV_UP if idev->cnf.mtu6 differs from
> >>>> dev->mtu,
> >>>>   >sysctl mtu6 is overwritten.
> >>>>   >
> >>>>   >So changing disable_ipv6 sysctl for some device may change mtu sysctl
> >>>>   >for it...
> >>>>
> >>>> eth0.mtu sysctl changed on step 4.
> >>>
> >>> Argh... Let's come with examples. Would you show the combination of
> >>> eth0/default
> >>> mtu/disable_ipv6 -s _in_ _images_ that would be restored wrongly if we
> >>> don't
> >>> make the check you suggest?
> >>
> > 
> > In images:
> > 
> > eth0.mtu = 1500
> > 
> > def_conf6.mtu=1280 def_conf.disable_ipv6=1
> > eth0.conf6.mtu=1280 eth0.conf6.disable_ipv6=0
> 
> OK. So you mean that when we create eth0, it will inherit mtu from default
> and will have it be 1280, but when we'll set eth0.disable_ipv6 to 0 the
> eth0.mtu will change to 1500. Right?

Yes. But now I see that even after creation it will be 1500 already.

> 
> -- Pavel
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